简介：LocalstructuresofthemolybdenumsulfidespeciesinthesultidedRh-Mo-K/Al2O3catalystswithvariousrhodiumloadingshavebeeninvestigatedbyXAFS.Fromthefittingresults.theMo-Mocoordinationnumberforthesamplefreeofrhodium(ca.3.7)issimilartothatforthecrystallineMoS2,indicatingthatthesupportedsulfidedmolybdenumspeciesmainlypresentaslargepatechesofMoS2-likeslabs.Fortherhodium-modifiedsamples,however,theamplitudesoftheMo-SandMo-Mocoordinationshellsaresharplyreduced,revealingahighdispersionoftheMoS2-likespeciesinthecatalysts,TheschemeofthemicrostructuresofthesulfidedmolybdenumspeciesstabilizedonthealuminasupportisdiscussedbasedupontheanalysisoftheEXAFSdata.

简介：

简介：

简介：Aseriesofrhodium-modifiedMo-K/Al2O3catalystsampleswaspreparedbyvaryingtherhodiumloadingbetween0and1.0wt%andmaintainingmolybdenumandpotassiumcontentsasconstants.ThestructuresofthesampleswerecharaterizedbytechniquesofXRD.LRS.TPR,XPSandEXAFSandcorrelatedtothecatalyticpropertiesofthesamplesforalcoholsynthesisfromsynthesisgas,Itwasfoundthat.intheoxidicrhodium-modifiedsamples.astronginteractionoftherhodiummodifierwiththesupportedK-Mo-Ospeciesoccurs.Thisinteractionfacilitatesthesulfidationandreductionofthesupportedoxo-molybdenumandleadstoadecreaseinthesizeofthemolybdenumspeciesandstabilizationofthecationicrhodiumspeciesonthesamplesduringsulfidation.Uponsulfidation.Thesulfidedmolybdenumspeciesintherhodium-freesampleismanlypresentaslargepatechesofMoS2-likeslabswiththeirbasalsulfurplanesinteractingwiththesupportsurface.Withthemodiricationofrhodiumtothesamples.ThesupportedMoS2-likespeciesbecomeshighlydispersed.asrevealedbythedecreaseintheaveragesizeofthesulfidedmolybdenumspecies.TheinteractionoftherhodiumspecieswiththemolybdenumsomponentmaycausethebasalplanesoftheMoS2-likespeciestobecomeorientedperpendiculartothesupportsurfaceduetofavorablebondingoftheMoS2edgeplanestothesupportthroughMo-O-Albonds.Incomparisonwiththesulfidedsamplefreeofrhodium.thepropertiesoftherhodium-modifiedsamplesforalcoholsynthesisfromsynthesisgasaremuchimproved.Itmostprobablyresultsfromthesynergicinteractionoftherhodiumwiththemolybdenumspeciesthatgivesrisetotheappearanceofthecatalyticallyactivesurfacesofsites.Theco-existenceofcationicandmetallicrhodiumstabilizedbythisinteractionmayberesponsiblefortheincreasedselectivityfortheformationofC2+alcohols.

简介：AseriesofoxideizedCO-K-Mo/γ-Al2O3catalystsamples,preparedbyimpregnatingoxidizedK-Mo/γ-Al2O3sampleswithanaqueoussolutionofcalculatedCo(NO3)2andthencalcininginairattemperaturesof350℃，500℃65℃and800℃respectively,weresulfidedandtheninvestigatedfortheactivityinthesynthesisofmixedalcoholsfromCOhydrogenationunderconditionsofp=5.0MPa,T=350℃andGHSV=4800h^-1.TheresultsdemonstratethattheadditionofcobaltpromoterisfavorabletotheformationofhigheralcoholsandtheopimumcalcinationtemperaturesafterimpregnatingwithCo^2+areabout500-650℃.ThestructureofCoandMospeciesontheoxidizedandsulfidedsampleswasdeterminedbyX-raydiffraction(XRD),laserRamanspectrum(LRS)andextendedX-rayabsorptionfinestructure(EXAFS).Foroxidizedsamplecalcinedat350℃,cobaltexistsasCo3O4spectiesandcoversthesurfaceofK-Mo-Ospecies,thestructureofK-Mo-OspeciesisthesameasthatinK-Mo/Al2O3sample.TheinteractionbetweencobaltandK-Mo-Ospeciesisrelativelyweak.Aftersulfidation.Cobaltexistsassulfidecrystalliteswithanoctahedralcoordinatedstructure,andmolybdenumasMoS2crystallites.Foroxidizedsamplescalcinedat500-650℃,CocomponentinteractswiththeK-Mo-Ospeciesanddestroysthelong-rangeorderoftheK-Mo-Ospectesgradually,Aftersulfidation.CotendstoexistasasulfidewithtetrahedralcoordinatedstructureandMostillasMoS2crystallites.Foroxidizedsamplecalcinedat800℃,CocomponentexistsmainlyasCoAl2O4species,mostofwhichcannotbesultidedduringsulfidation.

简介：

简介：采用XRD、EXAFS技术研究了不同Pd含量的Pd-Mo-K/Al2O3催化剂结构，并关联其合成低碳混合醇性能。结果表明，在氧化态Mo-K/Al2O3催化剂体系中添加Pd后，“K－Mo”物相晶粒变小，分散度提高，说明钯可能和钾钼物种发生了较强的相互作用。经硫化还原处理后，发生了氧硫交换，钼主要以MoS2物种形式存在，其粒度随着Pd含量的增加而明显减小。尺寸的显著变化可能导致MoS2与载体作用形式的改变，从而影响CO加氢催化反应的性能。在硫化态催化剂中，Pd的添加不仅能提高CO加氢合成醇的收率和选择性，而且有利于改善产物的分布。基于以上结果，认为“K－Mo”作用物种和Pd物种均为合成醇的催化活性组份，它们间的相互协同作用使催化剂性能得到显著改善。

简介：

简介：A60%Fe/Al2O3catalystwaspreparedbytheco-precipitationmethod.ItwasreducedbyH2toproducemetallicFe,whichwasthensulfidedbyCS2toFe0.96SandFe3S4orphosphidedbytriphenylphosphine(PPh3)inliquidphasestoFe2PandFeP.Itwasfoundthattheironsulfides(Fe0.96SandFe3S4)exhibitedthelowactivityforthehydrodesulfurization(HDS)reactions.TheHDSactivitywasalsolowontheFe(metal)/Al2O3andFe2P/Al2O3catalystssincetheywereconvertedintoFe0.96SandFe3S4duringtheHDSreactions.Incontrast,theFeP/Al2O3wasfoundtobestableandactivefortheHDSreactions.Inparticular,FeP/Al2O3possessedsignificantlysmallerFePparticlesthanFeP/C,leadingtothesignificanthigherHDSactivityofFeP/Al2O3thanFeP/C.

简介：ThecorrelationbetweenphasestructuresandsurfaceacidityofAl2O3supportscalcinedatdifferenttemperaturesandthecatalyticperformanceofNi/Al2O3catalystsintheproductionofsyntheticnaturalgas(SNG)viaCOmethanationwassystematicallyinvestigated.Aseriesof10wt%NiO/Al2O3catalystswerepreparedbytheconventionalimpregnationmethod,andthephasestructuresandsurfaceacidityofAl2O3supportswereadjustedbycalciningthecommercialγ-Al2O3atdifferenttemperatures(600–1200C).COmethanationreactionwascarriedoutinthetemperaturerangeof300–600Catdifferentweighthourlyspacevelocities(WHSV=30000and120000mL·g-1h-1)andpressures(0.1and3.0MPa).ItwasfoundthathighcalcinationtemperaturenotonlyledtothegrowthinNiparticlesize,butalsoweakenedtheinteractionbetweenNinanoparticlesandAl2O3supportsduetotherapiddecreaseofthespecificsurfaceareaandacidityofAl2O3supports.Interestingly,NicatalystssupportedonAl2O3calcinedat1200C(Ni/Al2O3-1200)exhibitedthebestcatalyticactivityforCOmethanationunderdifferentreactionconditions.LifetimereactiontestsalsoindicatedthatNi/Al2O3-1200wasthemostactiveandstablecatalystcomparedwiththeotherthreecatalysts,whosesupportswerecalcinedatlowertemperatures(600,800and1000C).ThesefindingswouldthereforebehelpfultodevelopNi/Al2O3methanationcatalystforSNGproduction.

简介：采用无压烧结法制备含CeO2的Mo/Al2O3材料,用MM-200型环-块式摩擦磨损试验机测试该材料在滑动干摩擦条件下的磨损行为,通过X射线衍射（XRD）和电子探针对其微观结构和磨损后的形貌进行研究和分析。结果表明,添加CeO2的烧结样品中出现CeAl11O18相,且随CeO2含量（体积分数）增加,CeAl11O18逐渐增多,Al2O3相应减少。当CeO2的体积分数为6%时Al2O3全部由CeAl11O18取代;CeO2的添加使Al2O3和CeAl11O18相边界处均呈现圆钝形貌,并且存在Mo、Al、O的相互扩散区域。磨损形貌表明,1730℃烧结的样品中出现摩擦转移层,当CeO2含量达到4%时,该摩擦转移层大量出现,从而改善材料的耐磨性。

简介：BondingofAl2O3tocuisperformeddirectlyusingTifoilattemperatureof1273K.Themicrostructureofthejointinterfaceisinuestigatedthroughscanningelectronmicroscope（SEM）,electron.probemicroanalysis（EPMA）andX-raydiffraction（XRD）.theeffectoftheinitialtifoilthicknessonthereactionlayerthicknessandthejointStrengthareinvestigated.

简介：

简介：

简介：HotcompressionbehaviorofTiC–Al2O3/AlcompositeswasstudiedusingtheGleeble-1500systematatemperaturerangeof300–550°Candatstrainraterangeof0.01–10.00s-1.TheassociatedstructuralchangeswerestudiedbyTEMobservations.Theresultsshowthatstressleveldecreaseswithdeformationtemperatureincreasingandstrainratedecreasing,whichcanberepresentedbyaZener–Hollomonparameterinanexponent-typeequationwithhotdeformationactivationenergyQof172.56kJ·mol-1.Dynamicrecoveryoccurseasilywhenstrainratesarelessthan10.00s-1.Dynamicrecrystallizationcanoccuratstrainrateof10.00s-1.

简介：0.5%Pt-K/γ-Al2O3catalystsforthesynthesisofo-phenylphenol(OPP)fromo-cyclohexenyl-cyclohexanone(dimer)dehydrogenationwerepreparedbymeansofatwosubsequentimpregnationmethod.Theeffectsofcatalystpreparationparameters,suchasKpromoters,calcination,andreductionconditions,wereinvestigated.TheresultsshowedthattheadditionofK2SO4toPt/γ-Al2O3catalystnotablypromotedtheselectivityofOPP,anditsoptimumcontentwasfoundtobe6%inmassfraction.ThehigheractivitywasobtainedwhenPt/γ-Al2O3catalystwascalcinedinnitrogenatmosphereat400―500°Candthenreducedatthesametemperaturefor3hinhydrogenatmosphere.TheconversionofthedimerandtheselectivityofOPPwerealwaysabove99%and90%,respectively,over0.5%Pt-6%K2SO4/γ-Al2O3catalystduringthepilotscaletestof8000h.

简介：

简介：MgO-Al2O3-Cr2O3rammingmixesmadeofdifferentrawmaterialshavedifferentmineralstructureanddifferentphysicalpropertiesthoughwiththeidenticalparticlesizedistribution,thesameamountofbinderandchemicalcomposition.Theresidualcarboncontentofthefusedmagnesia-chromematerialmadeinreducingatmosphereisveryhigh,ifthismaterialsisusedintheMgO-Al2O3-Cr2O3rammingmix,itwouldcausespallingofthefurnaceliningduringdrying-out.

简介：Themicrostructureandslagerosionfractaldimensionofreactioninterfaceofβ-Sialon-Al2O3brickusedin300MtironladleofBaosteelhavebeenstudiedbySEMandXRD.Theresultsindicatedthatβ-Sialon-Al2O3brickexhibitedexcellentslagresistance.Themainwearmechanismofβ-Sialon-Al2O3brickismainlyfromthespallingcausedbythermalmechanicalstressandattackedbyslagsecondly.

简介：